Telephone system



Dec. 21, 1943.

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Patented Dec. 21, 1943 TELEPHONE SYSTEM Pier Bakker, Chicago, Ill., assignor to Automatic Electric Laboratories, Inc., a corporation of Delaware Application December 15, 1941, Serial No. 423,063 Y 17 Claims.

The present invention relates to telephone systems and has for one of its objects the provision of improved apparatus for setting up monitoring connections through automatic switching equipment to busy called lines.

It is another object of the invention to provide in an automatic system of the character described, improved facilities for permitting toll operators to obtain access to busy called lines without permitting the subscribers `of theY system to have this service.

According to another object of the invention, provisions are made in each connector of the system whereby the monitoring facilities are to I a large extent used in the performance of other up connections to the lines of different types which are accessible to the connector.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be'understood by reference to the specification taken in connection-'with the accompanying drawings in which Figs. 1, 2A and 2B, 3A and 3B, 4A and 413, 5A and- 5B, 6A and 613, 7 and '8 to 13,'inclusive, when combinedin the manner shown in Fig. 15 illustrate an automatic telephone system having embodied therein the features of the invention as briey outline above, and Fig. 14 illustrates in schematic form the arrangement of the interrupter forming a part of the power supply and supervisory signaling equipment included in the system.

Referring now more vparticularly to the drawings, the telephone lines, automatic switching apparatus and power supply and supervisory signaling equipment there illustrated may comprise, for example, a small, Aunattended automatic exchange designed to serve a suburban area of limited population which is geographically adjacent severallargerl cities or towns, each of which is served by a central exchange- Inter-office 'trunks are usedto provide communi-- cation facilities between the small community exchange and the oii'ices provided in the adjacent `larger cities. For example, the automatic switching equipment of the community exchange is illustrated as having access to the automatic exchange 9 over a group of trunks which includes the trunk I 3. Similarly, groups of trunks are provided which extend between the community exchange and each of the other central oices. The trunk I3 is shown as terminating in the community exchange in arepeater I8 which is accessible to the links of the exchange through a line circuit I'I.

The subscriber lines .terminating at the community exchange may comprise single party or private lines, full metallic multiparty lines arranged for bridged ringing, full metallic multiparty linesarranged for divided ringing, and ground return lines. The `illustrated line I0 is shown as being ofthe single party type and is arranged toV serve onlythe substation A which may beeither a private `substation or a paystation. rIhis line terminates in the community exchange in a line circuit I4 which is of the form disclosed and claimed in Patent No. 2,199,534,

granted May 7, 1940,;Bier Bakker, and includes a mechanically interlocked linev relay RIO!) and cut-off relayRI I8. *Thev line circuit I4 also includes an outgoing ca ll meter !2 5 which operates to. register calls initiated on the linel I 0 only, and a vtotal call'meterjImiV which functions to' register al1 calls involving` the line Iregardless of whether they are outgoing or incomingcalls. A second subscriber line I I is illustrated in Fig. '7 of the drawings as'being of themultiparty type arranged to serve'thetwo substations B and C. The lines extending tothe line terminals of the links of the communityexchange may also include one or more groups of vbranch exchange trunks. One such trunk I2 is illustrated as terminating in the community exchangein the line circuit I6 and as extending to the switchboard of a private branch exchange 8,. The indicated line circuit as Well as the line circuits terminating the interv-office trunks and the line circuits terminating the other v(subscriber lines are each identical with the line circuit I4 described above.

The automatic'switching apparatus provided in the exchange for setting up connections between' the various lines terminating thereat com- 

